Cole Crops

Bacterial Blight

Pathogen: Pseudomonas syringae pv. alisalensis

Bacterial blight infections start as small, angular-shaped,
water-soaked specks on leaves that are often surrounded by yellow borders. As
the disease develops, specks enlarge and coalesce together into larger,
irregularly shaped gray-to-tan spots. Leafspots are visible from both top and
bottom sides of leaves. Symptoms may resemble those of the more familiar
bacterial leafspot disease.

Recent research has identified this bacterial disease, which is
caused by a pathogen related to, but distinct from, the bacterium that causes
bacterial leafspot. For cole crops, bacterial blight has been found on
broccoli, cauliflower, and Brussels sprouts. Other crucifer hosts include
rappini, arugula, and rutabaga. The pathogen is seedborne and is splashed from
plant to plant by rain and sprinkler irrigation. Bacterial inoculum may persist
for short periods of time in soil.

Plant clean and disease-free transplants. Rotation away from fields
where the disease has recently occurred may reduce inoculum levels in soil or
infected debris. A change from sprinkler to furrow or drip irrigation may limit
its spread.

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